1. Field of The Invention
The present invention relates generally to the recycling of nickel-cadmium batteries and, more particularly, to the recovery of metals from nickel cadmium battery scrap, unused Ni-Cd electrode materials, nickel cadmium battery process residues and the like. Specifically, the present invention relates to a simplified pyrometallurgical recovery process and device for recovering cadmium and nickel metal from scrap material containing the same.
2. Description of The Prior Art
Nonrechargeable, primary alkaline cells have long been a principal source for portable battery power in devices such as flashlights, tape recorders, calculators, radios and the like. Unfortunately, environmental disposal problems have made such cells less desirable and have provided a major impetus for the development of rechargeable secondary cell technology. To date, a principal rechargeable cell arrangement generally includes cells using cadmium and nickel. Unfortunately, these cells eventually do wear out and must themselves be disposed of, thus leading to additional environmental concerns.
Used electrical storage batteries contain metals whose recovery may be advantageous from a financial point of view as well as from an environmental position. The metals, as previously indicated, which are principally of interest for recovery are cadmium and nickel. There is a significant additional environmental interest in preventing cadmium from being released into the environment by arbitrary and indiscriminate scrapping or throwing away of batteries in landfills and the like. From various view-points, therefore, there is a significant desire to insure that used and scrapped Ni-Cd batteries are dealt with in a controlled and safe manner.
During nickel-cadmium battery manufacture, the various process residues from the manufacturing technology also contain nickel and cadmium as well as cobalt, other metals and oxides, hydroxides, hydrates and other compounds. The recycling or reuse of metals such as cadmium and nickel and certain of such process residues is also of interest.
Some prior techniques which have been previously utilized for recovering cadmium and other metals include chemical techniques as disclosed in U.S. Pat. No. 4,511,541. In addition, U.S. Pat. No., 4,793,933 discloses a process for extracting metals from waste treatment sludges utilizing both heat and chemical processing techniques.
U.S. Pat. Nos. 4,401,463 and 4,675,048 both disclose processes for recovering metals, and in particular nickel and cadmium, from electric storage batteries utilizing electrothermal processes. However, these processes are somewhat complex and require numerous processing stages and steps requiring in turn a wide variety of equipment interaction. In particular, U.S. Pat. No. 4,401,463 requires, by way of example, the transferring of materials to a variety of different locations for each of a variety of different steps.
Therefore, prior art techniques for recovering metals from scrap nickel-cadmium batteries as well as process residues have remained complicated and costly. Consequently, there is still a need for a simple yet effective process and technique for recovering cadmium and nickel metals from scrap materials containing the same for both environmental purposes as well as economical recycling purposes.